Electric circuit breaker



March 19, 1935. H. H.,KNOWLES ELECTRIC CIRCUIT BREAKER Filed June 13, 1929 [NI 'ENTOR.

Patented Mar. 19, 1935 Harry'H. Knowles, Birmingliani, Alaa a'ssignor v V to Southern States Equipment; Co, ,Birn ing:;

' ham, Ala.

Application June 13,1929, Serial No. 370,723

6 Claims.

When air-break circuit breakers of high capacity or for high voltage are located on a high steel supporting structure, the weights of the various parts often cause difficulty in operating the switch, particularly if the device is manually controlled.

The object' of my invention is to reduce or counter-balance some of the heavy parts so that there is less efiect of'gravity to be overcome and so that there is less frictional resistance developed as the switch is opened or closed.

Referring to the drawing, Fig. 1 shows an elevation of one of my switches mounted upon a steel structure. Only one phase of the switch is shown, but in practice three phases are usually mounted side by side, all being operated by the same horizontal square shaft. Fig. 2 shows an enlarged view of the switch and the control mechanism in closed position.

Fig. 3 shows a stillfurther enlarged view of one of the operating cranks attached to the square shaft.

Fig. 4 shows details of the switch in an open position to the same scale as Fig. 2.

On the base 1 are mounted two insulators 2 and 3 carrying the jaws and hinge of the switch blade 4. A movable insulator member 5 is pivoted'to the blade 4 by the pivot 17 and is supported at its other end by the pivot 18 and the swing member 6. The member 6 is pivoted, at its upper end to the base 1 by the pivot 16.

The insulator member 5. is also connected, through the pivot 19 to the link 7 and the link 7 is pivoted to the crank 8 by the pivot 20. The crank 8 is fastened to the square horizontal operating shaft 9. This shaft is carried in bearing bushings in the usual way. By means of the connecting members 10, 11, 12 and 13, the operating shaft is controlled by the handle member 14 in a self-evident way.

The new feature is that midway between the shaft 9 and the handle 14 the rocking member 12 is located; and this member 12 is pivoted at its center to a suitable support. The weights of the members 11 and 13 therefore counterbalance each other, and this is a great advantage when the switch has to be placed possibly forty or fifty feet above the handle 14. The handle 14 is suitably pivoted to a base 15.

On large switches, the weight of each insulator unit is often over a hundred pounds, and this is also an important factor in switch operation. Supporting the inner end of the insulator 5 by the swing 6, as shown, makes the grounded end of the insulator member go up as the outer end,

are a single rigid unit proportioned as shown in Fig. 4 with 6 omitted. This requires that much' of the weight of the member 5 has to be borne by the shaft 9 and its large diameter bearings.

I have found that the total friction is greatly reduced by my method of supporting the weight of the member 5 by pivots of small diameter, and keeping the bearings of the shaft 9 free from all friction except that due to its own weight and to the power transmitted.

Furthermore, since each switch unit is balanced as explained above, the power to be transmitted by the shaft is reduced and this results in still further improvement.

In order to reduce the weight of the square shaft9 while still retaining the square shape to which cranks are so easily attached, I use a square hollow shaft. This greatly reduces the weight without seriously reducing the torsional moment of the shaft.

I claim:---

1. In an electric circuit breaker, an insulator bodily movable in a generally horizontal direction, a swingarm at each end of the insulator, a pivot at each end of the insulator connecting the swing arm to the insulator and so supporting the insulator, the said swing arms being so located and proportioned that one of said pivotsis movable in an ascending arc and the other pivot is movable simultaneously in a descending arc.

, 2. In an electric circuit breaker, an insulator bodily movable in a generally horizontal direction, a swing arm at each end of the insulator, a pivot at each end of the insulator connecting the swing arm to the insulator and so supporting the insulator, the said swing arms being so located and proportioned that one of said pivots is operable in a descending arc and the other pivot is simultaneously operable in an ascending arc, togetherwith a second pivot at one end of the insulator, independent of the supporting pivots, for moving the insulator.

3. In an electric circuit breaker, a switch arm operable by a mechanism which includes an insulator bodily movable in a generally horizontal direction, a supporting pivot at each end of the insulator, one of the pivots being supported by the switch arm, a swing arm supporting the other of said pivots, the said switch arm and swing arm being so located and proportioned that one of the said pivots is movable in an ascending arc and the other, pivot is movable simultaneously in a descending arc.

4. In an electric circuit breaker, a switch arm,

the other end of the insulator; together with means independent of the said swing arm.for

moving the insulator.

5. In an electric circuit breaker, an insulator" bodily movable in a generally horizontal direction, a swing arm supporting each end of the insulator, together with an operating member pivotally connected to the insulator, the said operating member supporting none of the weight of the insulator.

6. In an electric switch, an insulator bodily movable in a generally horizontal direction, a swing arm at each" end of the insulator and connected with the insulator by a pivot, the two swing arms being so located and so proportioned that one of said pivots is movable in an ascending. arc and the other is simultaneously movable in a descending arc.

HARRY H. KNOWLES. 

